2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
3 * Licensed under the GPL
16 #include <sys/ptrace.h>
19 #include <asm/unistd.h>
21 #include "kern_constants.h"
24 #include "ptrace_user.h"
25 #include "registers.h"
26 #include "skas_ptrace.h"
28 static int ptrace_child(void *arg)
31 int pid = os_getpid(), ppid = getppid();
34 change_sig(SIGWINCH, 0);
35 if (ptrace(PTRACE_TRACEME, 0, 0, 0) < 0) {
37 os_kill_process(pid, 0);
42 * This syscall will be intercepted by the parent. Don't call more than
45 sc_result = os_getpid();
48 /* Nothing modified by the parent, we are running normally. */
50 else if (sc_result == ppid)
52 * Expected in check_ptrace and check_sysemu when they succeed
53 * in modifying the stack frame
57 /* Serious trouble! This could be caused by a bug in host 2.6
58 * SKAS3/2.6 patch before release -V6, together with a bug in
59 * the UML code itself.
65 static void fatal_perror(char *str)
71 static void fatal(char *fmt, ...)
83 static void non_fatal(char *fmt, ...)
93 static int start_ptraced_child(void **stack_out)
99 stack = mmap(NULL, UM_KERN_PAGE_SIZE,
100 PROT_READ | PROT_WRITE | PROT_EXEC,
101 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
102 if (stack == MAP_FAILED)
103 fatal_perror("check_ptrace : mmap failed");
105 sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
106 pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
108 fatal_perror("start_ptraced_child : clone failed");
110 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
112 fatal_perror("check_ptrace : clone failed");
113 if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
114 fatal("check_ptrace : expected SIGSTOP, got status = %d",
121 /* When testing for SYSEMU support, if it is one of the broken versions, we
122 * must just avoid using sysemu, not panic, but only if SYSEMU features are
124 * So only for SYSEMU features we test mustpanic, while normal host features
127 static int stop_ptraced_child(int pid, void *stack, int exitcode,
130 int status, n, ret = 0;
132 if (ptrace(PTRACE_CONT, pid, 0, 0) < 0)
133 fatal_perror("stop_ptraced_child : ptrace failed");
134 CATCH_EINTR(n = waitpid(pid, &status, 0));
135 if (!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
136 int exit_with = WEXITSTATUS(status);
138 non_fatal("check_ptrace : child exited with status 2. "
139 "\nDisabling SYSEMU support.\n");
140 non_fatal("check_ptrace : child exited with exitcode %d, while "
141 "expecting %d; status 0x%x\n", exit_with,
148 if (munmap(stack, UM_KERN_PAGE_SIZE) < 0)
149 fatal_perror("check_ptrace : munmap failed");
153 /* Changed only during early boot */
154 int ptrace_faultinfo = 1;
157 int skas_needs_stub = 0;
159 static int __init skas0_cmd_param(char *str, int* add)
161 ptrace_faultinfo = proc_mm = 0;
165 /* The two __uml_setup would conflict, without this stupid alias. */
167 static int __init mode_skas0_cmd_param(char *str, int* add)
168 __attribute__((alias("skas0_cmd_param")));
170 __uml_setup("skas0", skas0_cmd_param,
172 " Disables SKAS3 usage, so that SKAS0 is used, unless \n"
173 " you specify mode=tt.\n\n");
175 __uml_setup("mode=skas0", mode_skas0_cmd_param,
177 " Disables SKAS3 usage, so that SKAS0 is used, unless you \n"
178 " specify mode=tt. Note that this was recently added - on \n"
179 " older kernels you must use simply \"skas0\".\n\n");
181 /* Changed only during early boot */
182 static int force_sysemu_disabled = 0;
184 static int __init nosysemu_cmd_param(char *str, int* add)
186 force_sysemu_disabled = 1;
190 __uml_setup("nosysemu", nosysemu_cmd_param,
192 " Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
193 " SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
194 " behaviour of ptrace() and helps reducing host context switch rate.\n"
195 " To make it working, you need a kernel patch for your host, too.\n"
196 " See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
197 " information.\n\n");
199 static void __init check_sysemu(void)
202 unsigned long regs[MAX_REG_NR];
203 int pid, n, status, count=0;
205 non_fatal("Checking syscall emulation patch for ptrace...");
206 sysemu_supported = 0;
207 pid = start_ptraced_child(&stack);
209 if (ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
212 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
214 fatal_perror("check_sysemu : wait failed");
215 if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
216 fatal("check_sysemu : expected SIGTRAP, got status = %d",
219 if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
220 fatal_perror("check_sysemu : PTRACE_GETREGS failed");
221 if (PT_SYSCALL_NR(regs) != __NR_getpid) {
222 non_fatal("check_sysemu got system call number %d, "
223 "expected %d...", PT_SYSCALL_NR(regs), __NR_getpid);
227 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, os_getpid());
229 non_fatal("check_sysemu : failed to modify system call "
234 if (stop_ptraced_child(pid, stack, 0, 0) < 0)
237 sysemu_supported = 1;
239 set_using_sysemu(!force_sysemu_disabled);
241 non_fatal("Checking advanced syscall emulation patch for ptrace...");
242 pid = start_ptraced_child(&stack);
244 if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
245 (void *) PTRACE_O_TRACESYSGOOD) < 0))
246 fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
250 if (ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
252 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
254 fatal_perror("check_ptrace : wait failed");
256 if (WIFSTOPPED(status) &&
257 (WSTOPSIG(status) == (SIGTRAP|0x80))) {
259 fatal("check_ptrace : SYSEMU_SINGLESTEP "
260 "doesn't singlestep");
261 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
264 fatal_perror("check_sysemu : failed to modify "
265 "system call return");
268 else if (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
271 fatal("check_ptrace : expected SIGTRAP or "
272 "(SIGTRAP | 0x80), got status = %d", status);
274 if (stop_ptraced_child(pid, stack, 0, 0) < 0)
277 sysemu_supported = 2;
280 if (!force_sysemu_disabled)
281 set_using_sysemu(sysemu_supported);
285 stop_ptraced_child(pid, stack, 1, 0);
287 non_fatal("missing\n");
290 static void __init check_ptrace(void)
293 int pid, syscall, n, status;
295 non_fatal("Checking that ptrace can change system call numbers...");
296 pid = start_ptraced_child(&stack);
298 if ((ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
299 (void *) PTRACE_O_TRACESYSGOOD) < 0))
300 fatal_perror("check_ptrace: PTRACE_OLDSETOPTIONS failed");
303 if (ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
304 fatal_perror("check_ptrace : ptrace failed");
306 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
308 fatal_perror("check_ptrace : wait failed");
310 if (!WIFSTOPPED(status) ||
311 (WSTOPSIG(status) != (SIGTRAP | 0x80)))
312 fatal("check_ptrace : expected (SIGTRAP|0x80), "
313 "got status = %d", status);
315 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
317 if (syscall == __NR_getpid) {
318 n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
321 fatal_perror("check_ptrace : failed to modify "
326 stop_ptraced_child(pid, stack, 0, 1);
331 extern void check_tmpexec(void);
333 static void __init check_coredump_limit(void)
336 int err = getrlimit(RLIMIT_CORE, &lim);
339 perror("Getting core dump limit");
343 printf("Core dump limits :\n\tsoft - ");
344 if (lim.rlim_cur == RLIM_INFINITY)
346 else printf("%lu\n", lim.rlim_cur);
349 if (lim.rlim_max == RLIM_INFINITY)
351 else printf("%lu\n", lim.rlim_max);
354 void __init os_early_checks(void)
356 /* Print out the core dump limits early */
357 check_coredump_limit();
361 /* Need to check this early because mmapping happens before the
367 static int __init noprocmm_cmd_param(char *str, int* add)
373 __uml_setup("noprocmm", noprocmm_cmd_param,
375 " Turns off usage of /proc/mm, even if host supports it.\n"
376 " To support /proc/mm, the host needs to be patched using\n"
377 " the current skas3 patch.\n\n");
379 static int __init noptracefaultinfo_cmd_param(char *str, int* add)
381 ptrace_faultinfo = 0;
385 __uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param,
386 "noptracefaultinfo\n"
387 " Turns off usage of PTRACE_FAULTINFO, even if host supports\n"
388 " it. To support PTRACE_FAULTINFO, the host needs to be patched\n"
389 " using the current skas3 patch.\n\n");
391 static int __init noptraceldt_cmd_param(char *str, int* add)
397 __uml_setup("noptraceldt", noptraceldt_cmd_param,
399 " Turns off usage of PTRACE_LDT, even if host supports it.\n"
400 " To support PTRACE_LDT, the host needs to be patched using\n"
401 " the current skas3 patch.\n\n");
403 static inline void check_skas3_ptrace_faultinfo(void)
405 struct ptrace_faultinfo fi;
409 non_fatal(" - PTRACE_FAULTINFO...");
410 pid = start_ptraced_child(&stack);
412 n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
414 ptrace_faultinfo = 0;
416 non_fatal("not found\n");
421 if (!ptrace_faultinfo)
422 non_fatal("found but disabled on command line\n");
424 non_fatal("found\n");
428 stop_ptraced_child(pid, stack, 1, 1);
431 static inline void check_skas3_ptrace_ldt(void)
436 unsigned char ldtbuf[40];
437 struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
438 .func = 2, /* read default ldt */
440 .bytecount = sizeof(ldtbuf)};
442 non_fatal(" - PTRACE_LDT...");
443 pid = start_ptraced_child(&stack);
445 n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
448 non_fatal("not found\n");
456 non_fatal("found\n");
458 non_fatal("found, but use is disabled\n");
461 stop_ptraced_child(pid, stack, 1, 1);
463 /* PTRACE_LDT might be disabled via cmdline option.
464 * We want to override this, else we might use the stub
471 static inline void check_skas3_proc_mm(void)
473 non_fatal(" - /proc/mm...");
474 if (access("/proc/mm", W_OK) < 0) {
479 non_fatal("found but disabled on command line\n");
480 else non_fatal("found\n");
483 int can_do_skas(void)
485 non_fatal("Checking for the skas3 patch in the host:\n");
487 check_skas3_proc_mm();
488 check_skas3_ptrace_faultinfo();
489 check_skas3_ptrace_ldt();
491 if (!proc_mm || !ptrace_faultinfo || !ptrace_ldt)
497 int __init parse_iomem(char *str, int *add)
499 struct iomem_region *new;
505 file = strchr(str,',');
507 printf("parse_iomem : failed to parse iomem\n");
512 fd = open(file, O_RDWR, 0);
514 os_print_error(fd, "parse_iomem - Couldn't open io file");
518 if (fstat64(fd, &buf) < 0) {
519 perror("parse_iomem - cannot stat_fd file");
523 new = malloc(sizeof(*new));
525 perror("Couldn't allocate iomem_region struct");
529 size = (buf.st_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
531 *new = ((struct iomem_region) { .next = iomem_regions,
538 iomem_size += new->size + UM_KERN_PAGE_SIZE;